(a) Field of the Invention
The present invention relates to the security systems and, in particular, it concerns a system that observes the surveillance zone with stereo camera and analyses if there is an intruder or not in the area
(b) Description of the Related Art
The modern level of technology makes it possible to develop intellectual security systems to make business and private life more safe and convenient. Intruder detector is an automatic system that detects intrusion of any human body into surveillance zone. Surveillance zone is the area that must be protected with intruder detector, including offices, banks, private homes or any other buildings, any area that is not the open space. Since last years different technical solutions have been proposed for this area.
One example of an attempt to make a solution of this problem is the intruder detection system disclosed in U.S. Pat. No. 5,910,767. In this method the light beam from laser scans the surveillance zone and reflects from the target that might be the potential intruder and computer measures and analyzes the distance and intensity of the reflected light and sounds an alarm if detected person is an intruder. However, this method has several serious disadvantages. First, it uses intermediate optics (mirror, equipment for its rotation and so on) that can give a substantial part of error in intruder's detection and additional noise to the input scene. Indeed, usage of laser can occupy additional time to scan the surveillance area to receive data about all points of the scene and there are limits in spectral range based on chosen type of laser. Furthermore, price of some types of lasers can be very high and the spectral range can be not appropriate to work both under dark and with daylight illumination. Thus, the method of U.S. Pat. No. 5,910,767 is highly limited in potential applications.
Similarly, U.S. Pat. No. 4,364,030 discloses another intruder detection system. This system includes infrared sensor, optical system and electronic system for processing of image data. However, because of infrared sensor usage the level of false alarm for this system is much higher because of the reaction of sensor on the heat flows that can be not only from the human intruder.
Another example is disclosed in Pat. of Russian Federation No. 95115528/09. This method involves two-stage recognition. First stage includes matching personal code of person and password which he/she utters. Then device for scanning face according to person's height is loaded and face image is scanned and compared to stored data. If there is a correspondence between these characteristics the system detects the object. This system is the system of protection of the entering of surveillance zone from unauthorized access. However, this method has several big disadvantages. First, this method is non convenient for authorized user because he needs to remember the input data and to do something to enter the area. Also, this method permits only the entrance of the intruder but it cannot monitor the whole surveillance zone if there is an intruder. So because of those disadvantages it has serious limits in potential applications.
In general, there are a lot of different methods in the field of intruder's detection using different kinds of sensors and computer or processor for sensor's signal processing.
However, such a limitation implies to develop method that have both low price of the equipment and low level of false alarms and noise in input images. Such system can detect intruder more efficiently using stereo camera for observing the surveillance zone and special digital signal processor for images processing with high speed and good quality.